The present invention relates to controlling the positioning of a workpiece on a machine tool or similar device on three axes, so that a planar and straight surface can be machined onto a workpiece, or the ultimate straight motion can be applied to the workpiece for a measurement or adjustment purpose.
U.S. Pat. No. 4,602,459 issued Jul. 29, 1986 discloses a control system for precision machine tools and similar devices that utilizes a workpiece support having a flexible hinge connection from a base to a support block. The position of the support block is controlled by an actuator moving in response to a sensor that senses deviations of a straight line of a reference surface carried on the support from its initial position.
The device of U.S. Pat. No. 4,602,459 maintains a straight line, in most instances, but it can have deviations from a straight line since only one sensor is utilized. If the workpiece happens to pivot about the contact point between the sensor and the reference surface, a curved surface can be ground or machined on the workpiece, while the sensor is not indicating any deviation of the reference surface from its initial position.
The device of the present invention eliminates deviation from straight line motion and provides a straight, planar machined surface by including a pair of sensors moving along a straight and flat reference surface that maintain the piece part in a straight axis as it moves relative to a machine tool, and a third sensor which provides a signal indicating deviations of the reference surface and the piece part from its positioning along a third axis.